2020 Chevrolet Blazer: check engine light

Filed Oct 22, 2026 · Engine, Steering · MI

2020 Chevy Blazer LT 3.6 L V6 I'm filing this complaint regarding multiple concerning mechanical and safety related issues with my 2020 Chevy Blazer LT that I purchased brand new and currently have 54,224 miles . Without warning, My vehicle developed several problems simultaneously. The check engine light came on, The engine cooling fan started running continuously at high speed, the AC stopped blowing cold air and is warm air, the steering assist reduced came on and my chevy app notified me that I have an engine cooling system malfunction and to service now. It's showing a P0128 code when I had it checked. After doing some research, I discovered GM issued a thermostat special coverage program for certain vehicles 2021-and newer models. Mine isn't part of it because of the year and isn't covered by the power train warranty for the same reason even though they all have the same engine. I only have 54,000 miles! I'm very concerned over the steering assist being reduced! What if the steering goes out while I'm driving? I have my grandchildren all the time. I need my car! There are several other complaints on here for the same vehicle and the same problem! Why isn't the 2020 Blazer covered under this special coverage program? The dealerships all say it's a well known problem! I believe this issue deserves investigation !

Filed Sep 14, 2026 · Engine · 119,000 miles · OH

The contact owns a 2020 Chevrolet Blazer. The contact stated that while operating the vehicle, the check engine warning light intermittently illuminated, and the vehicle hesitated while accelerating. The vehicle was taken to the local dealer to be diagnosed, and the contact was informed that the catalytic converter needed to be replaced. The vehicle was not yet repaired. Additionally, while operating the vehicle, the engine temperature rose to HOT. The vehicle was taken to the local dealer, and the thermostat was replaced. The manufacturer was notified of the failure. The failure mileage was 119,000.

Filed Jul 10, 2026 · Brakes, Engine · AK

I was driving and steering reduced drive with caution notification and brake assist notification came on and then engine light and the temp gage went to cold and stayed there. My steering stiffened up making it hard to steer. This is a known problem with the Chevy blazers and it had to do with the thermostat needing replaced.

Filed May 26, 2026 · OK

Variable Valve Timing (VVT) exhaust Solenoid engine light has been coming on and turning off immediately for a few months, finally found the issue. $665 replacement.

Filed May 7, 2026 · Brakes, Engine · IA

The check engine light came on with a warning that said "Steering assist reduced drive with care". The temperature gauge went to cold and the air condition quit working.

Filed Apr 17, 2026 · Electrical, Engine · TX

2020 Chevy Blazer RS 3.6L V6: having intermittent issues with ‘check engine’ light activating and giving code P0128 - indicating “Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)”. Symptoms include: - Temp gauge drops to reading “C” (cold), - AC blows warm/hot air, - Dash displays message, “Steering Assist is Reduced, Drive with Care”, - Radiator (electric) fans run full speed. It seems that the computer is interpreting the engine coolant temperature sensor drop as a ‘stuck open’ thermostat, thus the indicated code. However, at the same time it also appears to assume a bad coolant temp sensor, and failsafes to disable the AC and set the radiator fans to max to avoid potential overheating. The problem with this is that this can occur after driving for some period that the engine is suitably warm, then I can pull off the road, disconnect the battery for a few minutes, and everything goes back to normal operation. A broken thermostat would not behave this way. * This happened in Mar 2025 - after disconnecting the battery about 5-6 times over about a 1wk period the code cleared and we were able to pass inspection. The issue did not reoccur until about the same time this year. It has been recurring periodically since. * After reading numerous postings on this issue, with numerous different vehicles that have this engine and computer, I have no faith that the dealership will provide a solution other than charging me to replace the thermostat, and ending up with the same problem a few weeks later.

Filed Apr 9, 2026 · Engine · AR

2020 Blazer, 65,000 miles. Temp stuck on cold, A/C blows warm aor and driving assistance off. The radiator fan runs continuously. Check engine light on.

Filed Apr 7, 2026 · Engine, Steering · MI

| Issues first appeared recorded on 3/9/2026, while odometer read 49,663 miles. Check engine light was caused by error codes P0128 and P01F0. This causes the following issues: * Check engine light to appear on the dashboard. * Engine temperature gauges to be unreliable at times or completely non functional at others, as it will constantly read the engine temperature "Cold". * Air conditioning unit to become unreliable at times or completely non functional at others, and only blow hot air. * Radiator fan will be stuck running at max speed despite current engine temperature. * A "Reduced Steering Assist" message will periodically appear on the dashboard. * A "Service ESC" message will periodically appear on the dashboard. * Remote start will becomes non functional. | Car was taken to a license Chevrolet dealership and had full thermostat housing and thermostat sensors replaced. Dealership confirmed all replaced parts are working correctly and as intended. After picking up the vehicle from the dealership, and driving car for roughly 30 miles, the check engine light appeared on the dashboard again causing all previous issues to return. | Several other Chevy Blazer 2020 owners have complained of the same issue online, and in forums such as: [XXX] . | INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Mar 10, 2026 · Engine · MI

P0128 code for thermostat issue. Fans run after shutting car off. Steering assist reduced message. Check engine light. Chevy knows this is a common issue. This needs to be investigated asap.

Filed Feb 18, 2026 · Engine, Transmission · 70,000 miles · TX

The contact owns a 2020 Chevrolet Blazer. The contact stated that while driving at an undisclosed speed, the check engine warning light illuminated. The vehicle was taken to an independent mechanic, where it was diagnosed with VVT sensor failure. The sensors were replaced; however, the failure recurred. The vehicle was taken back to the mechanic, where a solenoid was replaced. The vehicle was repaired. The contact was informed that if the failure recurred, there might be an internal engine failure. The dealer was not contacted. The manufacturer was notified of the failure and referred the contact to the federal safety agency Hotline to report the failure. The failure mileage was approximately 70,000.

Filed Feb 4, 2026 · Electrical, Engine · MI

I received a check engine light which i took to Bell tire for diagnosis. Here is there diagnosis Comments: The P01F0 code on a 2020 Chevy Blazer means the engine coolant temperature is below the normal operating range, often due to a stuck-open thermostat (or both thermostats in models with dual units), a faulty Engine Coolant Temperature (ECT) sensor, or low coolant, leading to poor fuel economy and potential wear; fixing it usually involves replacing the thermostat(s) or sensor after checking coolant levels and wiring. After that i took the vehicle to GM Dealership. Even though this is a know issue with many vehicles from same year, i was told that my VIN is not part of recall and dealership ended up charging me 600+ to fix the issue. I am reaching out to seek help as i had exact same problem but GM is not covering the repairs because my VIN is not in the recall. How is that possible?

Filed Jan 16, 2026 · Electrical, Steering · LA

Action required steering assist reduced and coolant temperature at 0. Air con blowing hot and check engine light on. The vehicle became hard to handle and keep in my lane on the interstate at high speeds. The problem has persisted. It has not been recitfied. I am not driving the car to avoid damage and danger. I bought the blazer on 1/6/26. The lights and issues began 8 days later. Dealership will not help me. 2020 Blazer RS AWD bought from Morgan city Toyota Louisiana